With just three games left, Juventus have a four-point lead and could wrap up a seventh straight league title next weekend.
Koulibaly, the hero who scored the last-gasp header that kept Napoli’s ambitions alive with a 1-0 win over Juventus in Turin last week, was sent off after just eight minutes.
Argentina forward Simeone — the son of Atletico Madrid boss Diego Simeone — scored all three goals in a spectacular display to keep Fiorentina’s Europa League hopes alive.
Maurizio Sarri’s side fell four points behind Juventus who battled past 10-man Inter Milan in a 3-2 San Siro thriller on Saturday night with two late goals in three minutes.
Massimiliano Allegri’s side play at home against Bologna on Saturday and could win the Scudetto if Napoli fail to win at home against Torino on Sunday.
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